1. Field of the Invention
The present invention relates to a semiconductor device and semiconductor device manufacturing method.
2. Description of the Background Art
In a power semiconductor module, a semiconductor chip or the like is fixed with solder to one main surface of an insulating substrate, and a radiating member is fixed with solder to the other main surface of the insulating substrate.
However, in such a power semiconductor module, when the solder repeatedly expands and contracts due to temperature change occurring when operating, notches or the like may occur in the solder. Further, thermal strain concentrates in the notches, whereby fatigue damage occurs in the solder, which may cause breakdown or damage of the power semiconductor module.
Therefore, in order to restrict the occurrence of notches or the like in the solder, the following kind of technology is known. A plurality of pillars with a thermal expansion coefficient higher than that of the solder is disposed between the insulating substrate and radiating member, and the gap between the insulating substrate and radiating member is widened by the expanded pillars when the solder is heated. Therefore, the melted solder is raised upward, the solder is prevented from collapsing or flowing under its own weight, and the solder strain concentration is reduced by depressing the end portion inwardly (for example, refer to JP-A-2001-168492).